CRYOGENIC PROCESS FOR SIMULTANEOUS SELECTIVE DESULFURIZATION AND DEGAZOLIZATION OF A GAZEOUS MIXTURE MAINLY MADE OF METHANE AND OF SOME H_S AND C_ OR HIGHER HYDROCARBONS

摘要

abstract Cryogenic process for the selective desulphurisation and simultaneous stripping of a gaseous mixture consisting primarily of methane and also containing H 2 and C 2 hydrocarbons and more. Said gas mixture, after having possibly undergone a débenzolage then a refrigeration producing condensate is washed between 0 ° C and -45 ° C by means of a selective solvent of the H2S to produce a methane stream in which the partial pressure of H2S is below 65 Pa and a liquid phase rich in H2S and containing at least 80 mol% of the C3-hydrocarbons and the gaseous mixture. The liquid phase is subjected to a demethanizer producing a rich solvent demethanised and a gaseous phase rich in methane, then the solvent is sufficiently cooled between -25 ° C and -80 ° C to cause the phase separation into a lower liquid fraction, which contains H2S and, in methane equivalent, less than 5 mol% hydrocarbon, and an upper liquid fraction formed of C3 hydrocarbons and more. Said fractions are separated and the fraction undergoes regeneration to produce an acid gas stream enriched in H2S and containing the aforementioned low oil content and a regenerated solvent.